The invention relates to slurry-cast double base propellants and, in particular, to crystalline oxidizer-fuels used with such propellants.
Cyclotetramethylenetetranitramine (HMX) is a crystalline oxidizer-fuel commmonly incorporated into slurry-cast double base propellants which, as is known, employ binder materials to promote mechanical adhesion. However, the propellant binder does not adhere to the smooth facets of the HMX crystals. Consequently, when the cured propellant is subjected to external loads of certain magnitudes, a phenomenon known as crystal `dewetting` occurs. In other words, the binder pulls away from the crystals and the crystals are ejected from the propellant surface. The mechanical properties of the propellant are significantly limited by this occurence since the reinforcing effect of the filler on the binder strength is not realized.
The present invention provides a polymeric coating for the crystals which avoids the `dewetting`and improves the mechanical properties of the propellant.